ch 3 Flashcards
what is the cell theory
- all living things are composed of one or more cells
- single cell is the smallest unit that exhibits all the characteristics of life
- all cells come from preexisting cells
how are cells classified
according to their internal organization…cellular structure
2 types that cells are classified as
*prokaryotic cells-not divided into membrane-bound compartments
*eukaryotic cells-divided into membrane-bound compartments (organelles)
what is the structure of eukaryotic cells
*plasma membrane
*nucleus -membrane bound genetic material
*cytoplasm-internal cell contents, includes cytosol
*organelles- membrane bound structures in cytoplasm with specialized functions
structure of prokaryotic cell
*plasma membrane
* rigid cell wall (covers plasma membrane)
*cytoplasm
*genetic info is not enclosed by a membrane
* no membrane-bound organelles
what do all cells do
gather raw materials, excrete wastes, synthesize macromolecules, grow and reproduce
*all have a specialized function of some sort
metabolic activities of a cell are proportional to?
volume of cytoplasm
in what ways does a high surface-to-volume ratio promotes efficiency
-getting nutrients
- disposing wastes
what do microvilli do/what are they
small projections of the cytoplasmic membrane that increases surface area
types and uses of each mircoscope
*light microscope
- up to 1000x
-for living samples
*transmission electron microscope
-up to 100000x
-shows internal details of cell structure
*scanning electron microscope
-up to 100000x
- 3D view of cell surface
nucleus
controls the cell, info centre
ribosomes
synthesize proteins
endoplasmic reticulum
manufacturing center
golgi apparatus
refines, packages and ships
vesicles
membrane bound storage and shipping containers
mitochondria
provides energy
function and structure of nucleus
*controls and contains genetic info
*double layered nuclear membrane
*nuclear pore-permits passage of rna and proteins
*chromosomes- dna
* nucleolus-site of synthesis of ribosome components
what is responsible for protein synthesis
ribosomes
what does ribosomes do/ what are they made of
-rna and protein
-site of protein synthesis
locations of ribosomes-2 places
free-floating in cytoplasm…synthesize proteins for immediate use
bound-attached to outer surface of endoplasmic reticulum…synthesize proteins that will be transported to other organelles or exported from cell
endoplasmic reticulum has?
- highly folded membranous network
- Rough ER (ribosomes on surface)
- smooth ER
function of rough ER
manufacture proteins to be modified in the ER…to be secreted from cell
function of smooth er
*lipid synthesis…also synthesis of some hormones
* packages proteins and lipids for delivery to golgi apparatus
function of golgi apparatus
*refines synthesized products
*serves as packaging and shipping centre
*packaged into vesicles and shipped to other places in cell or to cell membrane for export
types of vesicles
*secretory vesicles-contains products that will be exported from cell
*endocytic vesicles-contains substances imported from the external environment
*peroxisomes-contains enzymes that detoxifies wastes
*lysosomes-contains digestive enzymes
function of mitochondria
*generates ATP…powerhouse of cell
*site of cellular respiration (uses O2 and produces CO2)
*provides energy
structure of mitochondria
*double membrane
*inner membrane is highly folded
-divides mitochondria into an inner compartment and an outer compartment
*inner compartment is surrounded by inner membrane
*outer compartment is between inner and outer membrane
sources of energy that are in a cell not enclosed by a membrane
fat:
-triglycerides
- long term energy storage in animals
- stored in cytoplasm of fat cells
glycogen:
-carb storage
- short term energy storage
- stored in cytoplasm of muscle cells and liver cells
what are structures that are for support and movement in cells
*cytoskeleton-internal scaffolding that maintains cell shape
* structures that enable movement:
- cilia
- flagella
- centrioles
what is cytoplasm made of
*microtubules-tiny hollow tubes of proteins
* microfilaments- tiny solid fibers of protein
*both from framework that supports the cell
where and describe cilia
*short, many hairlike projection
*on cells lining airways and some ducts
where and describe flagella
*long, single
*enable spermatozoa to swim
where and describe centrioles
*short rod like microtubular structures near nucleus
*important role in cell division
what is the plasma membrane composed of
*phospholipid-two layer (bilayer)
- polar head out and nonpolar tail inside
*cholesterol- increases mechanical strength
*proteins- provide means of transport through membrane for molecules and for info
what is a fluid mosaic
phospholipid and proteins are not anchored and drift relative to each other
ways to cross the plasma membrane
*passive transport-no energy
-diffusion
- osmosis
- facilitated diffusion
*active transport-needs energy
*bulk transport-membranous vesicles to move larger substances
- endocytosis
- exocytosis
what does passive transport rely on?
diffusion
what is diffusion
*high conc to low conc
*needs conc gradient
*if has same concentration throughout= equilibrium
*only effective in the body over short distances
osmosis
*diffusion of water across a selectively permeable membrane
*low solute conc to high solute conc
*water moves down its own concentration gradient
osmotic pressure
fluid pressure required to exactly oppose osmosis
3 forms of passive transport
*diffusion directly through the lipid bilayer-small lipid soluble…small, uncharged, nonpolar molecule ex. O2
*diffusion through protein channels-ex. h2o, ions
* facilitated transport (facilitated diffusion)…binding of a specific molecule to a membrane transport protein causes a change in the shape of the protein which then carries the molecule through the membrane bilayer. highly selective. ex. glucose
active transport
*lower conc to higher conc
*against conc gradient
*requires a membrane protein (transporter or pump)
*needs ATP
endocytosis (bulk transport)
*brings stuff into cell
*some vesicles are selective and have receptors for specific substances ex transport of insulin into cells
process of endocytosis
-substance in the extracellular environment is surrounded by the cell’s plasma membrane and internalized…forming a membrane-bound vesicle
exocytosis
expels substances from cell
-release of wastes, indigestible material and secretion of special products
process of exocytosis
-substance is contained within a membranous vesicle, which then fuses with the plasma membrane, releasing the substance to the external environment
what do receptor proteins do
*span membrane
*required for transmission of info to and from cell
what do receptor sites do/where are they
*interact specifically with signal molecules
*on receptor proteins
how is a change triggered?..receptor
triggered within the cell as a result of binding of signal molecule to receptor site
Na+/ K+ pump
*maintains cell volume by moving ions in and out of cell
* 3 Na+ in, 2 K+ out
tonicity definition
relative concentration of solutes in two fluids
isotonic
extracellular and intracellular solute concentrations are equal
what are the 2 variations in tonicity
*hypertonic
- shrink and die
- water leaves (osmosis)
-extracellular solute concentration higher than intracellular solute conc
*hypotonic
-extracellular solute concentration lower than intracellular solute conc
-osmosis into cell
- swells and burst (lysis)
what is metabolism
sum of all chemical reactions in an organism (can be branched, linear or cyclic pathways)
two types of metabolic processes
*anabolism-builds larger molecules from smaller, needs energy input
ex. proteins from amino acids
*catabolism-break down big to small, releases ATP
why do metabolic activities require a lot of energy
*builds large complex macromolecules
*powers active transport
*fuel movement such as muscle contraction
*energy is often provided by the catabolism of ATP
how many ATP can one glucose molecule yield
36
what is cellular respiration
breakdown of glucose in the presence of oxygen to yield atp
*uses O2 and produces CO2 in the process of making ATP
4 stages of cellular respiration
*glycolysis
*preparatory step
*citric acid cycle
*electron transport system and oxidative phosphorylation
process of glycolysis
-in cytoplasm
- 10 reactions that split glucose into 2 pyruvates
- net yield is 2 ATP
-NADH forms
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process of preparatory step
*two pyruvates enter mitochondria
*pyruvates become acetyl groups and CO2
*NADH forms
*Acetyl CoA forms and enters citric acid cycle
process of citric acid cycle
-harvests energy
- inner compartment of mitochondria
- cyclic series of 8 reactions to break down acetyl coA
- forms NADH and FADH2
- 2 ATP and 4 CO2 per glucose molecule
process for the ETC and oxidative phosphorylation
-produce ATP
- in the inner mitochondrial membrane
- consists of a number of electron carriers arranged in the membrane
-takes electrons from NADH and FADH2 and they go to the chain of electron carriers and the energy lost by the electrons is transferred to the electron carriers
- final electron acceptor is O2
summary of energy production from glucose
*20 different enzyme-catalyzed reactions
*cell respiration released the energy in glucose slowly
*energy originally in glucose is captured in the bonds of ATP
*approx 36 ATP (net) produced for each molecule of glucose
additional energy sources
*glycogen=1% of total energy reserves
- rapidly catabolized to glucose then cellular respiration happens
*fats= 78% of total energy reserves
- triglycerides have twice the energy of an equal amount of carbs
*proteins= 21% of total energy reserves
-same amount of energy as carbs
what are fats broken down to?
*glycerol
- converted to glucose in the liver
- converted to pyruvic acid and enter citric acid cycle
*fatty acids
- broken down to 2-carbon acetyl groups that enter citric acid cycle as acetyl coA
primary role of proteins
enzymes or structural components
- protein catabolism increases during starvation
what are proteins are broken down to amino acid
-amine groups are removed from amino acids then converted to urea and excreted in urine
- carbon backbones of amino acids enter various points of the citric acid cycle
what do anaerobic pathways do
make energy available without oxygen
what happens when there no O2 (anaerobic)
*glycolysis will continue
* pyruvate will build up and be converted to lactic acid
*limited ATP production-2 ATP per molecule of glucose
*once O2 becomes available, lactic acid will be metabolized aerobically
